When setup_fields() function finds field named '*' it expands it to the list
of all table fields. It does so by checking that the first char of
field_name is '*', but it doesn't checks that the '* is the only char.
Due to this, when updating table with a field named like '*name', such field
is wrongly treated as '*' and expanded. This leads to making list of fields
to update being longer than list of the new values. Later, the fill_record()
function crashes by dereferencing null when there is left fields to update,
but no more values.
Added check in the setup_fields() function which ensures that the field
expanding will be done only when '*' is the only char in the field name.
depending on table order
multi_update::send_data() was counting updates, not updated rows. Thus if one
record have several updates it will be counted several times in 'rows matched'
but updated only once.
multi_update::send_data() now counts only unique rows.
Date field was declared as not null, thus expression 'datefield is null'
was always false. For SELECT special handling of such cases is used.
There 'datefield is null' converted to 'datefield eq "0000-00-00"'.
In mysql_update() before creation of select added remove_eq_conds() call.
It makes some optimization of conds and in particular performs conversion
from 'is null' to 'eq'.
Also remove_eq_conds() makes some evaluation of conds and if it founds that
conds is always false then update statement is not processed further.
All this allows to perform some update statements process faster due to
optimized conds, and not wasting resources if conds known to be false.
thd->allow_sum_func was left 'true' after previous statement thus allowing
sum funcs to be present in conditions.
thd->allow_sum_func should be set to 0 for each query and each prepared
statement reinitialization. This is done in lex_start() and
reset_stmt_for_execute().
disabled if ref is built with a key from the updated table
Problem was in add_not_null_conds() optimization function.
It contains following code:
JOIN_TAB *referred_tab= not_null_item->field->table->reginfo.join_tab;
...
add_cond_and_fix(&referred_tab->select_cond, notnull);
For UPDATE described in bug report referred_tab is 0 and dereferencing it
crashes the server.
Don't produce data truncation warnings from within cp_buffer_from_ref(). This function
is only used to make index search tuples and data truncation that occurs here has no
relation with truncated values being saved into tables.
